1. Field of the Invention
The present invention relates to a chip, and more particularly to a chip having a metal pillar structure.
2. Description of the Related Art
FIG. 1 shows a cross-sectional view of a conventional chip having a metal pillar structure. The conventional chip 1 having a metal pillar structure comprises a chip body 11, at least one chip pad 12, a first passivation layer 13, an under ball metal layer (UBM) 14 and at least one metal pillar structure 15. The chip body 11 has an active surface 111. The chip pad 12 is disposed on the active surface 111. The first passivation layer 13 is disposed on the active surface 111, and has at least one first opening 131 so as to expose part of the chip pad 12. The under ball metal layer (UBM) 14 is disposed on the chip pad 12. The metal pillar structure 15 is disposed on the under ball metal layer (UBM) 14, and comprises a metal pillar 16 and a solder 17. The metal pillar 16 is disposed on the under ball metal layer (UBM) 14, and has a peripheral surface 161. The solder 17 is disposed on the metal pillar 16, and the maximum diameter formed by the solder 17 is greater than the diameter of the metal pillar 16, so that the solder 17 protrudes outside of a phantom zone extending upward from the peripheral surface 161 of the metal pillar 16.
The conventional chip 1 has the following disadvantages. When the pitch between two adjacent metal pillar structures 15 of the chip 1 is a fine pitch, and the maximum diameter formed by the solder 17 is greater than the diameter of the metal pillar 16, a solder bridge easily happens, which leads to a short circuit.
Therefore, it is necessary to provide a chip having a metal pillar structure to solve the above-mentioned problems.